From time to time, you will find a device that wants to talk ModbusRTU/ASCII that you just cannot make talk. The baud rate, data bits, stop bits, and parity are all set correctly. You still cannot get it to talk. You have tried using the "Frame Timing Detect" settings in Crimson and none of them work. The default timing for ModbusRTU Frames, if the baudrate is 19200 or higher, is 1.75ms.
If you have 10 devices on the RS485 network and 2 are talking just fine but the other 8 are not talking no matter how you set up crimson, a good place to look is if the device gives you the ability to set up the frame time.
This exact scenario was discovered, and it was found out that the manufacturer of the 8 devices had set up their device with a ModbutRTU frame timing of 3ms. Once the timing was set to 1.75ms, all devices on the RS485 network port started talking.
**Please note as this is an important point...
This does not affect any device on the network that already has the default frame timing of 1.75ms, ONLY the devices that are not set to this default setting. Any device with the default setting will communicate. This may look like a bad wiring or bad product scenario, but it is a setting in the RS485 port communications settings.